The Origin and Evolution of Vertebrates

These flashcards cover key vocabulary and concepts related to the origin and evolution of vertebrates, focusing on chordates, their characteristics, and major groups.

Chordates

Animals belonging to the phylum Chordata, which possess a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Notochord

A long, flexible rod that provides support in chordates, typically retained as a skeletal element in vertebrates.

Dorsal hollow nerve cord

A tube-like structure that develops into the central nervous system in chordates.

Pharyngeal slits

Openings that allow water to pass from the mouth to the outside of the body in chordates.

Post-anal tail

An extension of the body that extends beyond the anal opening in chordates.

Gnathostomes

Vertebrates that possess jaws.

Tetrapods

Gnathostomes that have four limbs.

Amniotes

Tetrapods that have a terrestrially adapted egg.

Echinodermata

A phylum of marine animals characterized by a calcareous endoskeleton and radial symmetry.

Myxini

Class of jawless fishes known as hagfishes.

Petromyzontida

Class of jawless fishes known as lampreys.

Chondrichthyes

Class of cartilaginous fishes that includes sharks and rays.

Actinopterygii

Class of bony fishes known as ray-finned fishes.

Actinistia

Class of lobe-finned fishes, which include coelacanths.

Dipnoi

Class of lungfishes that possess both lungs and gills.

Amphibia

Class of tetrapods that includes frogs, salamanders, and caecilians.

Reptilia

Class of amniotes that includes turtles, snakes, lizards, and birds.

Mammalia

Class of amniotes that are characterized by mammary glands and hair.

Eutherians

Placental mammals that give birth to live young.

Metatherians

Marsupials, whose young complete development in a pouch.

Prototherians

Monotremes, egg-laying mammals.

Cephalization

The development of a head region where sensory organs and the brain are concentrated.

Bipedal locomotion

Movement characterized by walking on two legs.

Hominins

Group that includes modern humans and their close extinct relatives.

Evolution

Change in the heritable traits of biological populations over successive generations.

Tetrapod characteristics

Features such as four limbs, neck, and a fused pelvic girdle associated with tetrapods.

Extraembryonic membranes

Membranes that support the embryo in amniotic eggs, including the amnion and chorion.